Well I am a larger fellow, business casual dress, sometimes with a coat, sometimes without, and never carried before. I am looking to spend what ever is appropriate for something that will last. I think this might be to large for IWB, and MS is concealed carry only.
I would recommend an IWB holster with offset loops or clips. These will thin the holster out some (if the loop is right on the holster body the thickness of the loop adds to the thickness of the gun, causing a larger than needed bulge) and aid in stabilizing the gun.
There are many other fine holster maker out there, there are just a few. Also, if the holster you order doesn't work out, a quality holster can be easily re-sold.
Depending on how large a guy you are I would take a look first at Tucker Gunleather's Texa Heritage. Yes, its on the expensive side but as it's a tuckable holster you could have your shirt tucked into your pants with the gun under it. I carry my XD frequently that way (Comp-Tac CTAC holster). The access is slower but you still have a gun with. Also, once you decide where to get a holster from you might as well order a good gunbelt at the same time. Also, you don't have to tuck your shirt in over the gun but if the holster can do it, its an option. If you chose to go this route, you might want to order a second set of kydex clips for the holster that are the velcro style (your belt would need to have the matching velcro as well).
I feel that I should add that I've never owned or saw a Tucker holster but I've heard great things about them. I've owned 2 Sparks holsters and they were great (sold one with the gun and still have the other one but I sold the gun).
FYI, part way through writing this post I grabbed my 4" M65 out of the safe to see how well it would work IWB (been toying with the idea of getting a basic leather IWB holster for it). I'm not a big guy (5'6" 160lbs or so) and I think I could conceal my M65 without any issues.